linux-kernel - [PATCH v3 0/7] mm: Page fault enhancements

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Message-Id: <20190911071007.20077-1-peterx@redhat.com>
Date:   Wed, 11 Sep 2019 15:10:00 +0800
From:   Peter Xu <peterx@...hat.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     David Hildenbrand <david@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Maya Gokhale <gokhale2@...l.gov>,
        Jerome Glisse <jglisse@...hat.com>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Johannes Weiner <hannes@...xchg.org>, peterx@...hat.com,
        Martin Cracauer <cracauer@...s.org>,
        Marty McFadden <mcfadden8@...l.gov>, Shaohua Li <shli@...com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Denis Plotnikov <dplotnikov@...tuozzo.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mel Gorman <mgorman@...e.de>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>
Subject: [PATCH v3 0/7] mm: Page fault enhancements

v3:
- check fatal signals in __get_user_page_locked() [Linus]
- add r-bs

v2:
- resent previous version, rebase only

This series is split out of userfaultfd-wp series to only cover the
general page fault changes, since it seems to make sense itself.

Basically it does two things:

  (a) Allows the page fault handlers to be more interactive on not
      only SIGKILL, but also the rest of userspace signals (especially
      for user-mode faults), and,

  (b) Allows the page fault retry (VM_FAULT_RETRY) to happen for more
      than once.

I'm keeping the CC list as in uffd-wp v5, hopefully I'm not sending
too much spams...

And, instead of writting again the cover letter, I'm just copy-pasting
my previous link here which has more details on why we do this:

  https://patchwork.kernel.org/cover/10691991/

The major change from that latest version should be that we introduced
a new page fault flag FAULT_FLAG_INTERRUPTIBLE as suggested by Linus
[1] to represents that we would like the fault handler to respond to
non-fatal signals.  Also, we're more careful now on when to do the
immediate return of the page fault for such signals.  For example, now
we'll only check against signal_pending() for user-mode page faults
and we keep the kernel-mode page fault patch untouched for it.  More
information can be found in separate patches.

The patchset is only lightly tested on x86.

All comments are greatly welcomed.  Thanks,

[1] https://lkml.org/lkml/2019/6/25/1382

Peter Xu (7):
  mm/gup: Rename "nonblocking" to "locked" where proper
  mm: Introduce FAULT_FLAG_DEFAULT
  mm: Introduce FAULT_FLAG_INTERRUPTIBLE
  mm: Return faster for non-fatal signals in user mode faults
  userfaultfd: Don't retake mmap_sem to emulate NOPAGE
  mm: Allow VM_FAULT_RETRY for multiple times
  mm/gup: Allow VM_FAULT_RETRY for multiple times

 arch/alpha/mm/fault.c           |  7 +--
 arch/arc/mm/fault.c             |  8 +++-
 arch/arm/mm/fault.c             | 14 +++---
 arch/arm64/mm/fault.c           | 16 +++----
 arch/hexagon/mm/vm_fault.c      |  6 +--
 arch/ia64/mm/fault.c            |  6 +--
 arch/m68k/mm/fault.c            | 10 ++--
 arch/microblaze/mm/fault.c      |  6 +--
 arch/mips/mm/fault.c            |  6 +--
 arch/nds32/mm/fault.c           | 12 ++---
 arch/nios2/mm/fault.c           |  8 ++--
 arch/openrisc/mm/fault.c        |  6 +--
 arch/parisc/mm/fault.c          |  9 ++--
 arch/powerpc/mm/fault.c         | 10 ++--
 arch/riscv/mm/fault.c           | 12 ++---
 arch/s390/mm/fault.c            | 11 ++---
 arch/sh/mm/fault.c              |  7 ++-
 arch/sparc/mm/fault_32.c        |  5 +-
 arch/sparc/mm/fault_64.c        |  6 +--
 arch/um/kernel/trap.c           |  7 +--
 arch/unicore32/mm/fault.c       | 11 ++---
 arch/x86/mm/fault.c             |  6 +--
 arch/xtensa/mm/fault.c          |  6 +--
 drivers/gpu/drm/ttm/ttm_bo_vm.c | 12 +++--
 fs/userfaultfd.c                | 28 +-----------
 include/linux/mm.h              | 81 +++++++++++++++++++++++++++++----
 include/linux/sched/signal.h    | 12 +++++
 mm/filemap.c                    |  2 +-
 mm/gup.c                        | 69 ++++++++++++++++------------
 mm/hugetlb.c                    | 14 +++---
 mm/shmem.c                      |  2 +-
 31 files changed, 234 insertions(+), 181 deletions(-)

-- 
2.21.0